Deputy Prime Minister Bulent Arinc suggested the blast was caused by a bomb, although Ankara's governor said it may have been caused by a burning gas cylinder.

"I've been informed that there was an explosion in a car on Kumrular
Street, close to the PM's office, and there are heavy casualties," Arinc
said. It was "either known or understood" the blast was caused by a
bomb, he added.

A plume of thick smoke rose above the heart of
the city after the blast. Reuters reporters at the scene said a line of
parked vehicles had been destroyed and an adjacent row of shops was
damaged across the street from a primary school.

Ambulances and
fire engines rushed to the scene and police set up a security cordon
while bomb disposal teams' sniffer dogs searched for any possible
secondary device.

Ankara governor Alaaddin Yuksel said a witness
had reported that the blast was caused by a burning gas cylinder thrown
into the street, which caused a fire that blew up a car. The incident
was under investigation, he added.